Glüer C C, Wu C Y, Genant H K
Department of Radiology, University of California, San Francisco 94143.
Osteoporos Int. 1993 Jul;3(4):185-91. doi: 10.1007/BF01623674.
Quantitative ultrasound (QUS) techniques have recently been introduced as alternative methods free of ionizing radiation for non-invasive assessment of skeletal status in osteoporosis. We carried out an in vitro study on bone specimens to investigate whether broadband ultrasound attenuation (BUA) signals are associated with bone structure, specifically with the orientation of the trabeculae, and whether this association is independent of the association between orientation and bone mineral density (BMD) as measured by dual-energy X-ray absorptiometry (DXA). BUA and BMD of 10 cubical specimens of purely trabecular bovine bone were examined along the three principal axes. The relative orientation of the trabeculae with respect to the direction of the ultrasound beam was evaluated on high-resolution conventional radiographs employing a semiquantitative ALIGNMENT score ranging from -2 (for perpendicular) to +2 (parallel). BUA variability was 27.6 dB/MHz, reflecting both inter-specimen (18.2 dB/MHz) and intra-specimen (19.4 dB/MHz) variability at comparable levels and to a much lesser extent reproducibility errors (1 dB/MHz). BUA was 44%-54% larger along the axis of the compressive trabeculae as compared with the two perpendicular axes. BMD and ALIGNMENT showed independent significant associations with BUA. A change in ALIGNMENT from perpendicular to parallel corresponded to a difference in BUA of 36.1 dB/MHz. The substantial level of intra-specimen variability suggests that BUA reflects anisotropical characteristics of trabecular bone. The association of BUA and ALIGNMENT indicates that BUA signals depend of trabecular orientation. This association is independent of BMD, indicating that BUA has considerable potential for non-invasive assessment of bone structure and strength, free of ionizing radiation, and for complementing existing bone densitometry examinations.
定量超声（QUS）技术最近已被引入，作为一种无电离辐射的替代方法，用于骨质疏松症骨骼状态的无创评估。我们对骨标本进行了一项体外研究，以调查宽带超声衰减（BUA）信号是否与骨结构相关，特别是与小梁的方向相关，以及这种关联是否独立于双能X线吸收法（DXA）测量的方向与骨矿物质密度（BMD）之间的关联。沿着三个主轴检查了10个纯小梁牛骨立方体标本的BUA和BMD。在高分辨率传统放射照片上，采用范围从-2（垂直）到+2（平行）的半定量对齐评分，评估小梁相对于超声束方向的相对取向。BUA变异性为27.6 dB/MHz，反映了标本间（18.2 dB/MHz）和标本内（19.4 dB/MHz）在相当水平的变异性，以及在较小程度上的再现性误差（1 dB/MHz）。与两个垂直轴相比，沿着压缩小梁轴的BUA大44%-54%。BMD和对齐与BUA显示出独立的显著关联。对齐从垂直变为平行对应于BUA差异36.1 dB/MHz。标本内变异性的显著水平表明，BUA反映了小梁骨的各向异性特征。BUA与对齐的关联表明，BUA信号取决于小梁方向。这种关联独立于BMD，表明BUA在无电离辐射的情况下，对骨结构和强度进行无创评估以及补充现有骨密度检查方面具有相当大的潜力。
